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The present research is dedicated to the study of anaerobic co-digestion process of different biomass materials. Anaerobic co-digestion of digested sludge, grass silage, haylage and cattle manure was evaluated in mesophilic tank reactors in the lab-scale experiment. Twelve laboratory scale tank reactors (1.5 L) were used during the incubation period of 45 days. First triplet of reactors was fed with pure digested sludge and the other three with different mixtures having the volumetric ratios of 30/35/25/10, 40/30/20/10 and 50/25/15/10 for digested sludge/corn silage/grass haylage/cattle manure. Methane production was analyzed for all labscale reactors individually. The resulting specific methane production of above-mentioned batches was 336.34, 238.1 and 233.23 LSTP[CH4] kg-1 [TVS], respectively. Other results such as cumulative biogas and methane yield, volumetric biogas and methane yield, volumetric biogas and methane yield per day were also assessed. These results had the highest meaning when complex substrate had no more than 30% of inoculum

The utilization of biofuels in spark ignition and compression ignition engines is the trend of the recent time. The great expectations are inserted into n - butanol as a fuel, especially for spark ignition engines. The short time use of n - butanol in the SI (spark ignition) combustion engine does not make a big problem (start of the cold engine, change of the air - fuel ratio). The purpose of this contribution is the effect of long - term use of n - butanol as a fuel for SI engine. For this purpose the small portable generator was used. The harmful emissions, fuel consumption and power of the generator was measured then the generator was operated for 300 hours on 100% n - butanol with 80% of nominal load and the measurement was repeated. The g enerator was loaded with adjustable electrical resistance. As a reference fuel the petrol BA 95 with no bio - component was used. During the operation on n - butanol no technical problems occurred with the generator. After 300 hours of operation on n - butanol t he performance parameters slightly decreased with little impact on production of harmful emissions components.

The key catabolic enzymes of D-xylose, an important structural component of different agricultural wastes, were studied in cells of mutant strains of the xylose-assimilating yeast Pachysolen tannophilus. The evaluation of catalytic activity and cofactor specificity of xylose reductase (ЕС 1.1.1.307) and xylitol dehydrogenase (ЕС 1.1.1.9) confirmed the dependence of intracellular catabolic pathway for D-xy lose on the NAD×H/NADP×H ratio, formed under microaerobic conditions. The study of total activity of some NAD+ /NAP×H-dependent dehydrogenases revealed the metabolic characteristics of the yeast cells, which could ensure selective ethanol or xylitol production. Thus, the efficient involvement of D-xylose into the Embden–Meyerhof–Parnas pathway provided not only the high activities of xylose reductase and xylitol dehydrogenase, but also of 1-glycerophosphate dehydrogenase (EC 1.1.1.8) and lactate dehydrogenase (ЕС 1.1.1.27), respectively. The inhibition of activity of these enzymes led to selective production of xylitol from D-xylose. On the base of the experimental results, the principles of metabolic engineering of xylose-assimilating yeasts were formulated. The possibility of bioethanol and xylitol production from different agricultural wastes using xyloseassimilating yeasts are discussed.

This article addresses the problem that fluctuations in the torque of an internal combustion engine (ICE) lead to additional energy losses, as it causes fluctuations in the speed and kinetic energy of the car. These losses increase as the frequency of oscillations of the torque of the internal combustion engine approaches the frequency of free (natural oscillations) of the running gear of the car in the longitudinal direction. If there is an elastic connection between the traction force and the movement of the car, the movement of the latter can be represented as complex. At the same time, the portable movement is uniform, and the relative movement is oscillatory. This article presents the results of the study of these losses for cars with mechanical and combined electromechanical drive wheels. Analytical expressions are obtained, which allows to take into account additional energy losses including the tangential rigidity of the tire and the rigidity of the suspension in the longitudinal direction. When using a combined electromechanical drive of the drive wheels as well as in the case of a mechanical transmission of a car, the resonance is dangerous. But with the increase in the share of torque kem on the wheel generated by the electric motor, the relative additional energy losses for the movement of the car are reduced.

In the Federative Republic of Brazil, Jatoba ( Hymenaea courbaril ) and Garapa ( Apuleia leiocarpa ) trees are intensively harvested . The yield of one log is approximately 45 – 55%, which indicates a great amount of produced wood waste biomass.Present research monitored the suitability of wood waste biomass from Jatoba and Garapa trees for bio – briquette for solid biofuel production. The research was focused on chemical parameters, and energ y potential of such biomass kinds. Jatoba wood waste biomass was used for the production of bio – briquette fuel and its final mechanical quality was investigated by determination of their mechanical quality indicators. Results of chemical analysis (in wet b asis) exhibited great level of ash content in case of both species ( Jatoba – 0.31%, Garapa – 3.02%), as well as high level of energy potential; net calorific value equal to 18.92 MJ kg – 1 for Jatoba and to 18.39 5 MJ kg – 1 for Garapa. Analysis of elementary composition proved following levels of oxygen content: J atoba – 41.10%, Garapa – 39.97 %. Mechanical analysis proved bio – briquette samples volume density ρ equal to 896.34 kg m – 3 which indicated quality bio – briquette fuel , while the level of rupture force R F occurred at a lower level – 47.05 N mm – 1 . Most important quality indicator, the mechanical durability DU, unfortunately, occurred at a lower level; DU = 77.6% compared to the minimal level of bio – briquette fuels intended for commercial sales which must be > 90%. Overall analysis proved materials suitability for energy generation purpose with certain limitations which can improve by changing production parameters of briquetting.

The main parameters of the microclimate of pig farms are regulated by the norms of technological design. Naturally, such micro-climate parameters at real energy prices require high costs, but these are the most favourable conditions for the life of suckling piglets. According to the presented analysis, the problem of research is the need to provide a micro-climate in the room for comfortable keeping of pigs, which is currently achieved through high energy. The purpose of the development is to increase the efficiency of the microclimate of pig farms by using a mechatronic control system, rational use of utilized air energy and soil thermal potential with reduced energy costs of the ventilation system. The problem is solved by creating such a mechatronic system to ensure the microclimate of pig farms, which can: switch the direction of airflow to ensure the operation of the system in winter and summer; to control the movement of air, which must be disposed of according to the parameters of its quality; to provide a local microclimate in each place where animals are kept; rational use of soil thermal energy as a source of alternative energy; to carry out automatic pumping of the water necessary for humidification of air, and its utilization. The article presents the results of research of parameters of the developed mechatronic system of providing microclimate of pig premises, which were carried out in three stages: research of heat exchanger of side-evaporating type; substantiation of the ventilation system of polluted air intake; substantiation of the ventilation system for injecting clean air taking into account it's geothermal heating/cooling. The advantage of the proposed mechatronic system of the microclimate of pig farms is that it allows increasing the efficiency of microclimate by rational use of energy of utilized air (due to the use of side-evaporator type heat exchanger based on Maisotsenko cycle) and soil heat potential (geothermal energy) at low operating costs of the ventilation system through the additional provision of mechatronic elements. The presented results of numerical simulation of the indirect evaporative heat exchanger allow us to state that the cooling effect obtained in indirect evaporative channels can be quite high in comparison with traditional air conditioning patterns. The presented heat exchanger based on the Maisotsenko cycle (M-cycle) of considered heat carrier flow scheme is characterized by its high cost-effectiveness, low specific cost, small operational costs and structural simplicity, which is confirmed in the works. The models obtained in the Star CCM +software package can be used for optimization analysis of air-cooling with variations in the Reynolds number, humidity, channel length and geometric dimensions of channels. Because of analytical investigations of the contaminated air intake ventilation system, the method was developed and on its basis – the algorithm was implemented for the determination of geometrical arrangement of holes in the air duct of the mechatronic system for pigsty microclimate maintenance.

The research deals with problems of animal waste potential usage in order to produce biogas for energy generation in Ukraine. Although there are favorable conditions to develop biogas sector based on animal waste, the share energy, produced from it, is extremely low. The paper analyzes energy potential of agricultural biomass in Ukraine, economic tools, aimed at stimulating electricity generation from biogas based on animal waste, the results of their impact on biogas plants deployment. Among a number of barriers, which inhibit the development of this sector in Ukraine, the main ones are the need for significant initial investments to construct profitable biogas plants and a large amount of raw materials for their uninterrupted operation. Given the fact that 48.2% of farm animals are concentrated in small-scale farms and households, which cannot individually implement biogas projects, it is proposed to combine their financial and raw material resources within energy co-operatives. Economic benefits, which may be gained by small-scale farms within energy co-operative through the sale of electricity, generated from biogas, by feed-in tariff are calculated. It is discussed that in addition to economic benefits for small-scale farms owners, realization of the co-operative model in the bio-energy sector will let to obtain a number of ecological and social benefits both for territorial communities, and the state as a whole. International Journal of Sustainable Energy Planning and Management, Vol 18 (2018)

Nowadays fossil fuels are decreasing, causing the world's interest in renewable energy sources to rapidly grow. One of the most interesting renewable and ecologically pure fuels is biomass, which is considered to be carbon neutral. Biomass is a promising source of energy, as it can be used directly as an energy resource. Its quality characteristics such as gross calorific value and ash content are of paramount importance so as to improve the combustion process. Furthermore, during the last three decades, there has been an increasing interest in the production of biomass pellets for domestic and industrial use. Alternative feed stocks will need to be sourced to meet the demand for biomass pellets. Investigation for new energy crops that produce high amounts of biomass under low inputs and of high energy efficiency are the main tasks of this field. Therefore, the aim of this study is to assess the biomass yield and the quality characteristics (gross calorific value and ash content) of two perennial energy crops (Cynara cardunculus L. and Panicum virgatum L.) growing in a typical soil (Fluventic Xerochrept) of the main agricultural land of central Greece. The comparison for both cultivated crops was made in order to show the results during their 8th growing year. The examined factors were the irrigation (two levels: irrigated and rainfed) and the nitrogen fertilization (two levels: 0 and 80 kg N ha-1 ) as well as their effect on the dry biomass yield and the gross calorific value. It was found that higher dry biomass yield was produced from cardoon (21.3 vs. 14.23 t ha-1 ), while the higher average gross calorific value was observed for switchgrass biomass (17.31 vs. 15.65 Mj kg-1 ). Finally, multiplying the dry biomass yield (t ha-1 ) with the gross calorific value (Mj kg-1 ) it was found that 334 and 245 Gj ha-1 from a cardoon and a switchgrass cultivation could be produced, respectively. Cardoon has better results than switchgrass probably due to the fact that switchgrass is growing from March till October; while cardoon’s growing period is from October to June and in such areas precipitation is in shortage during summer months. Both crops could achieve high amounts of energy per hectare and thus their introduction in future land use systems, for an environmentally friendly energy production should be seriously taken into consideration.